A Saturn-Like Complex Composed of Macrocyclic Oligothiophene and C Fullerene: Structure, Stability, and Photophysical Properties in Solution and the Solid State.

A Saturn-like 1:1 complex composed of macrocyclic oligothiophene E-8T7A and C fullerene (C ) was synthesized to investigate the interaction between macrocyclic oligothiophenes and C in solution and the solid state. Because the Saturn-like 1:1 complex E-8T7A⋅C is mainly stabilized by van der Waals interactions between C and the sulfur atoms of the E-8T7A macrocycle, C is rather weakly incorporated inside the macro-ring in solution. However, in the solid state the Saturn-like 1:1 complex preferentially formed single crystals or nanostructured polymorphs. Interestingly, X-ray analysis and theoretical calculations exhibited hindered rotation of C in the Saturn-like complex due to interactions between C and the sulfur atoms. Furthermore, the photoinduced charge transfer (CT) interaction between E-8T7A and C in solution was investigated by using femtosecond transient absorption (TA) spectroscopy. The ultrafast TA spectral changes in the photoinduced absorption bands were attributed to the CT process in the Saturn-like structure.